VIEW 30
The holobiont
For most of the last 400 years, reductionism has been the engine of science: if you want to know how something works, break it down into its component parts and study them. This was the approach of botanists who would routinely put plant samples in a blender and then isolate the DNA. Extracting DNA like this was not simple, because the samples were plagued by contaminants—fungi, nematodes, archaea, and bacteria. But in 1994, biologist Richard Jefferson suggested that these were not “contaminants” but symbiotic organisms that contributed to the evolutionary fitness of the plant.
The microbes and the plant should be viewed together as a single unit—a “holobiont”.
A simple example of a holobiont is a coral. Scientists have long known that corals are a union of two species: polyps that create the calcium carbonate “skeleton” and algae that create nutrients through photosynthesis.
A simple example of a holobiont is a coral. Scientists have long known that corals are a union of two species: polyps that create the calcium carbonate “skeleton” and algae that create nutrients through photosynthesis. But where they once saw a duet, there is a growing realization that corals are really a whole choir of endolithic algae, polyps, prokaryotes, fungi, plastids, and viruses, all interdependent on each other.
You are not really “you” What is true for plants and corals is also true for animals. It is no longer possible to think of animals as distinct from the microbial communities they share a body with. A cow cannot digest grass, but the microbes that live in its stomach can. Cows’ bodies have evolved to house the microbes that sustain them. Similarly, the human gut contains about 1,000 major bacterial groups which together are called the “microbiome.”
The gene set of this microbiome is about 150 times larger than the human genome. In fact, 90% of the cells in a human body are bacterial so “you” are not really “you” but a holobiont—something to remember if you are “not quite feeling yourself today”. The microbiome is sometimes seen as a second brain, as it interacts with the enteric nervous system, the neurotransmitters in our gut that produce mood-influencing serotonin and communicate directly with the brain through the vagus nerve. This provides some scientific basis for “going with your gut instinct” or “butterflies in your stomach”. You actually have a type of brain down there.
De-perimeterization The holobiont concept has a mirror in the cyber realm in de-perimeterization; a clumsy word meaning the difficulty in distinguishing between “us” and “them” in cyber security.
If a company is using cloud-based services, are they inside or outside the corporate perimeter? What about contractors and third parties for software development or outsourced IT support? These considerations and the increase in working from home blur the dividing line between internal and external zones. Modern computer networks are a holobiont. This drives the growing Zero Trust movement, which does away with the perimeter concept and views everyone as untrustworthy until verified. See 5 Symbiogenesis and botnets
